High Pressure Torsion Extrusion (HPTE) is a severe plastic deformation (SPD) method that can be used to significantly increase the mechanical strength of bulk structural materials [1, 2].

In this study the effect of the microstructure and the crystallographic texture on microhardness, tensile strength and fatigue strength at room temperature of the magnesium alloy ZK60 (Mg-Zn-Zr) was investigated. The alloy was melted from high purity components and subsequently processed by direct extrusion with a strain of $\sim$ 3.8 and HPTE with a strain of $\sim$ 3.2. The structure and crystallographic texture of as-processed samples were analysed using scanning and transmission electron microscopy, as well as X-ray diffraction analysis. The results showed that the combination of axial crystallographic texture and grain refinement, along with the formation of precipitates during deformation, led to a high static (YS = 405 MPA, UTS = 450 MPa) strength of the alloy as well as to modified fatigue properties.

It is widely acknowledged that magnesium and its alloys are biocompatible and hold promise for the application as biodegradable bone implants [4]. However, the mechanical strength of the commercially-produced magnesium alloys is significantly limited, which in turn limits the commercial application of magnesium implants. Bulk samples (11 mm in diameter and 35 mm length) produced by HPTE, can be used for the production of screws, plates and rods used in the surgery practice [4].

[1] Y. Ivanisenko, R. Kulagin, V. Fedorov, A. Mazilkin, T. Scherer, B. Baretzky and H. Hahn, "High pressure torsion extrusion as a new severe plastic deformation process". Materials Science and Engineering: A, vol. 664, pp. 247-256, 2016.

[2] D. Nugmanov, A. Mazilkin, H. Hahn and Y. Ivanisenko, "Structure and Tensile Strength of Pure Cu after High Pressure Torsion Extrusion". Metals, vol. 9, 2019.

[3] B. L. Mordike and T. Ebert, "Magnesium: Properties — applications — potential". Materials Science and Engineering: A, vol. 302, pp. 37-45, 2001.

[4] F. Witte, "Reprint of: The history of biodegradable magnesium implants: A review". Acta Biomaterialia, vol. 23, pp. S28-S40, 2015.